Derivatives and Fair Value Measurements (Details 3) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014		Dec. 31, 2013
Gross amounts of recognized assets/liabilities [Member]
Derivative [Line Items]
Derivative assets, current	$ 8.9		$ 8.7
Derivative liabilities, current	129.4		215.8
Derivative assets, noncurrent	10.6		3.0
Derivative liabilities, noncurrent	129.1		264.1
Gross amounts of recognized assets/liabilities [Member] | Commodity swap contracts [Member]
Derivative [Line Items]
Derivative assets, current	4.3		8.7
Derivative liabilities, current	4.6		3.9
Derivative assets, noncurrent	1.8		2.8
Derivative liabilities, noncurrent	2.5		2.5
Gross amounts of recognized assets/liabilities [Member] | Foreign Currency Forward Contract [Member]
Derivative [Line Items]
Derivative assets, current	4.6		0
Derivative liabilities, current	124.8		211.9
Derivative assets, noncurrent	8.8		0.2
Derivative liabilities, noncurrent	126.6		261.6
Gross amounts offset in the condensed consolidated balance sheet [Member]
Derivative [Line Items]
Derivative assets, current	(6.1)		(2.3)
Derivative liabilities, current	(6.0)		(1.9)
Derivative assets, noncurrent	(10.0)		(1.1)
Derivative liabilities, noncurrent	(10.1)		(1.5)
Gross amounts offset in the condensed consolidated balance sheet [Member] | Commodity swap contracts [Member]
Derivative [Line Items]
Derivative assets, current	(1.5)		(2.3)
Derivative liabilities, current	(1.4)		(1.9)
Derivative assets, noncurrent	(1.2)		(0.9)
Derivative liabilities, noncurrent	(1.3)		(1.3)
Gross amounts offset in the condensed consolidated balance sheet [Member] | Foreign Currency Forward Contract [Member]
Derivative [Line Items]
Derivative assets, current	(4.6)		0
Derivative liabilities, current	(4.6)		0
Derivative assets, noncurrent	(8.8)		(0.2)
Derivative liabilities, noncurrent	(8.8)		(0.2)
Net amounts presented in the condensed consolidated balance sheet [Member]
Derivative [Line Items]
Derivative assets, current	2.8		6.4
Derivative liabilities, current	123.4		213.9
Derivative assets, noncurrent	0.6		1.9
Derivative liabilities, noncurrent	119.0		262.6
Net amounts presented in the condensed consolidated balance sheet [Member] | Commodity swap contracts [Member]
Derivative [Line Items]
Derivative assets, current	2.8		6.4
Derivative liabilities, current	3.2		2.0
Derivative assets, noncurrent	0.6		1.9
Derivative liabilities, noncurrent	1.2		1.2
Net amounts presented in the condensed consolidated balance sheet [Member] | Foreign Currency Forward Contract [Member]
Derivative [Line Items]
Derivative assets, current	0		0
Derivative liabilities, current	120.2		211.9
Derivative assets, noncurrent	0		0
Derivative liabilities, noncurrent	117.8		261.4
Derivatives not offset in the condensed consolidated balance sheet [Member]
Derivative [Line Items]
Derivative assets, current	(1.3)	[1]	(5.0)	[1]
Derivative liabilities, current	(1.5)	[1]	(5.4)	[1]
Derivative assets, noncurrent	(0.1)	[1]	(1.3)	[1]
Derivative liabilities, noncurrent	0.1	[1]	(0.9)	[1]
Net amount of derivatives not offset [Member]
Derivative [Line Items]
Derivative assets, current	1.5		1.4
Derivative liabilities, current	121.9		208.5
Derivative assets, noncurrent	0.5		0.6
Derivative liabilities, noncurrent	$ 119.1		$ 261.7

[1] Adjustments relate to the further netting of derivative contracts with a common counterparty across the Company's foreign currency, diesel fuel and explosives hedging strategy derivative contract portfolios that would be contractually enforceable in the event of default.